Re: [PATCH V3 11/16] migration: cpr-transfer mode

[Peter Xu <peterx@redhat.com>]

On Tue, Nov 19, 2024 at 04:03:08PM -0500, Steven Sistare wrote:
> On 11/19/2024 3:51 PM, Peter Xu wrote:
> > On Tue, Nov 19, 2024 at 03:32:55PM -0500, Steven Sistare wrote:
> > > This begs the question, should we allow channels to be specified in hmp migrate
> > > commands and for -incoming, in a very simple way?  Like with a prefix naming
> > > the channel.  And eliminate the -cpr-uri argument. Examples:
> > > 
> > > (qemu) migrate -d main:tcp:0:44444,cpr:unix:cpr.sock
> > > 
> > > qemu -incoming main:tcp:0:44444,cpr:unix:cpr.sock
> > > qemu -incoming main:defer,cpr:unix:cpr.sock
> > 
> > IMHO keeping the old syntax working would still be nice to not break
> > scripts.
> 
> The channel tag would be optional, so backwards compatible.  Its unambiguous
> as long as the channel names are not also protocol names.

Ah that's ok then.  Or maybe use "="?

  "main=XXX,cpr=XXX"

Then if no "=" it's the old?

> 
> > I was thinking we could simply add one more parameter for taking
> > cpr uri, like:
> > 
> >      {
> >          .name       = "migrate",
> >          .args_type  = "detach:-d,resume:-r,uri:s,cpr:s?",
> >          .params     = "[-d] [-r] uri [cpr_uri]",
> >          .help       = "migrate to URI (using -d to not wait for completion)"
> > 		      "\n\t\t\t -r to resume a paused postcopy migration",
> > 		      "\n\t\t\t Setup cpr_uri to migrate with cpr-transfer",
> >          .cmd        = hmp_migrate,
> >      },
> 
> That's fine.
> 
> I do like the incoming syntax, though, instead of -cpr-uri.  What do you think?

That'll definitely be lovely if possible, though would any monitor be alive
at all before taking a cpr stream, with this series alone?  I thought you
dropped the precreate, then QEMU isn't able to run the monitor loop until
cpr-uri is loaded.

-- 
Peter Xu